Method of producing nitrocellulose explosives



Patented June 2, 1925.

UNITED STATES 1,540,424 PATENT OFFICE.

.WAI TER PHILIP REGES'IEIN, OF WILMINGTON, DELAWARE, ASSIGNOR TO E. I.DU

POINT DE NEMOURS &

DELAWARE. I

COMI'ANY, OF WILMINGTON, DELAWARE, A CORPORATION 01' Manson or raonucmoNITROGELLULOSE ExrLosIvns.

No Drawing.

To all whom it may concern:

Be it knownthat I, WALTER PHILIP Race s'rmN, a citizen of the UnitedStates, and a resident of Wilmington, in the county of New Castle andState of Delaware, have invented a certain new and useful Method ofProducing Nitrocellulose Explosives, of'

which the following is a specification.

My invention relates to methods of producing nitrocellulose explosivesand has more particular relation to the art of increasing the porosityof dense nitrocellulose powders by incorporating a soluble solid in thenitrocellulose and ultimately dissolving out the solid, thereby to leavethe nitrocellulose porous, and, hence, fast burning and desirable foruse in practice ammunition, and in small calibre sporting rifles,pistols and revolvers.

Various methods involving this general feature have heretofore-beenproposed and the practice of incorporating a soluble solid innitrocellulose, and its ultimate removal, is well known. For. example,specific methods have been proposed for the use of sugar, saltpetre orother suitable salts, of barium nitrate and of sodium nitrate.

The present invention has not to do, therefore, merely with this wellknown practice of usin more particularly to a method which, by itsvarious features, adapts this practice to satisfactory and economicalcommercial use.

An object of the present invention is to provide a method, in theaforesaid art, whereby complications are avoided, a superior productproduced, and the solid body and the solvent for the nitrocelluloseconveniently removed and recovered from the product.

To this end, and also to improve generally upon methods of the characterindicated, my invention consists in the following matters hereinafterdescribed and claimed.

In general, in proceeding according to the present invention, in thepreferable manner, I use a mixture of nitrocellulose having certain ofits elements soluble in, and certain other of its elements not solublein, the solvent used for the colloiding: I perform the colloiding' ofthis mixture b treating it with a solution in which (as ust indicated)all elements of the mixture are not a soluble solid, but relatesApplication filed July 17, 1919. Serial No. 311,512.

soluble, and which solvent can be ultimately removed by the extractingagent used to remove the solid body that is usedfor obtainmg porosity,and simultaneously with the ('OllOKlIDg I add the said solid body andincorporate it with the nitrocellulose; I then form the colloid intograins by pressing through a die of say about-.05 inch in diameter andcutting the strings, say 100 to the inch; I then discharge the grainsdirectl y Into a solvent which is a solvent not only for the solventused for the nitrocellulose but also for the solidbody, thus removingboth the solid body and the solvent for the nitrocellulose at the sametime, and treat a sullicient time, and under such conditions as toremove both; I then drain and dry; and then I cool, expose to absorbmoisture, and perform the graphiting in the usual mannor.

'lhus, provide a process which not only gives a product of superiorporosity but also can be successively and economically carried outcon'unercially. The incorporation of the solid body simultaneously withthe colloiding and the use of a mixture of nitrocellulose all elementsof which are not soluble in the solvent used for colloiding-asdistinguished from the use of a solvent which is capable of dissolvingall the nitrocellulose but is only used sufliciently to partiallydissolve the nitrocellulose-gives a particularly satisfactory product;and use of such a solid body, and such a solvent for the nitrocellulose,that both body and solvent can be removed simultaneously with a sin lesolvent gives a method well adapted or economical use commercially.

Preferably I use a mixture of nitrocellulose part of which is, and partof which is not, soluble in a mixture of ethyl ether and ethyl alcohol,and various proportions of soluble to insoluble nitrocellulose may beused depending upon the powder desired, about 30 to 40% of soluble andto 60% of insoluble being generally satisfactory. And referably also, Iuse for the solid body rom 10 to parts of certain salts such aspotassium nitrate, sodium nitrate or sodium sulphate (preferablyanhydrous) that are soluble in water,the ethyl ether and ethyl alcoholbeing also soluble in water-and can be extracted from the granulatedpowder by the use of hot water of suitable temperaturefor a suitablelength of time.

The salts which I mention are examples of solids which are withoutinjurious action on the stability of the powder grain and can besubstantially wholly extracted from the powder grains by treatment withthe solvent for the solvent of the nitrocellulose and of the solid body.For example, with these salts even when 100 parts of salt areincorporated in 100 parts of nitrocellulose the amount of salts notextracted is less than But, of course, other bodies fulfilling thedesired conditions can be used.

As a specific example of my method I may proceed as follows :-134 partsby weight of dehydrated nitrocellulose containing 34 parts by weight ofethyl alcohol and 100 parts by -weight of nitrocellulose (l0 partssoluble andtit) parts insoluble, say) are mixed with 50 parts of veryfinely pulverized potassium nitrate in a suitable mixer and colloided bythe addition of about (56 parts by weight of ethyl ether (giving a ratioof ether to alcohol of about 2 to 1) with or without the use of brinerefrigeration, the time of mixing being sufiicient to insure a thoroughdistribution of the potassium nitrate throughout the colloid and fromone to three hours usually sutficing, depending upon the eiticiency ofthe mixer. The colloid after mixing is pressed into preliminary blocksby means of any suitable press and the blocks are then pressed throughdies having proper sized openings to give the desired diameter to thefinished grains; the strings of powder are taken from the die to agranulating or cutting machine and cut into grains of the desiredlength; from the cutting-machine the grains are discharged into water,the temperature of the water being maintained under C. and above theboiling point of ethyl ether, the water being preferably used in suchquantity that the boiling point of the solu tion is above 65 C. and theethyl ether is retained in the solution; the treatment being continuedfor four days, more or less, until substantially all salt and. allsolvent are both removed from the powder, the water being changedseveral times to render the extraction of the salts as complete aspossible; after the removal 01 the salt and solvent the powder isremoved from the water, allowed to drain and then dried at a temperatureof about 50 C. until the excess moisture is removed; the powder is thencooled, exposed to absorb moisture and graphited in the usual manner.

It will be understood that the systematic extraction of fresh portionsof powder grains with the water which has been used for the extractionof a previous portion of powder grains can be arranged to take place canbe obtained trom which the nitrocellulose solvent can be recovered andthe water evaporated and the salt recovered. Ev1- dently, variousmodifications of proportions, times, and temperatures, and so forth, mabe made without departure from the spirit of my invention. Also,although i I find highly desirable the use of a nitrocellulose mixturewh'ch is not wholly soluble in the solvent used, and, also, prefer touse such a solvent for the nitrocellulose, and such a solid body, thatboth may be removed simultaneously, it will be understood that certainfeatures of advantage of the invention may be retained though either ofthese features be not used.

It. will 'beseen that I have provided. in the art of increasing theporosity of dense nitrocellulose powder by incorporating a soluble bodyin the nitrocellulose and ultimately dissolving out the body, a methodwhereby complications are avoided, a superior product produced, and thesolid body and the solvent for the nitrocellulose eonveniently removedfrom the product.

Having thus described my in vcntion, what I claim as new is 1. Themethod of preparing nitrocellulose propellent powder which consists incolloiding a mixture of nitrocellulose having a portion not soluble in,and a portion soluble in,

the solvent used for colloiding, and incorporating a soluble solid bodyin the colloid, and then simultaneously, and in a sin 1e step, removingsaid solvent and said so id bod 2. The method of preparingnitrocellulose propellent powder which consists in colloiding, with amixture of ethyl ether and ethyl alcohol, nitrocellulose less than 50%of which is soluble in said mixture, incorporating a metal nitrate insaid nitrocellulose be fore the colloiding thereof is completed, formingthe resulting composition into grains, and then treating the latter withwater to extract, simultaneously, and in a single step, the ether,alcohol, and metal nitrate.

3. The method of preparing porous diepressed nitrocellulose propellent'powder which consists in eolloiding with a solvent mixture ofethyl-ether and ethyl alcohol, nitrocellulose less than 50% of which issoluble in said mixture, incorporating a watersoluble solid body in thecolloid, pressing the colloid through a die, cutting into grains thestrings so formed, and'then removing the solvent and solid body bytreating with water. 1

4. The method of preparing nitrocellulose propellent powder whichconsists in colloiding nitrocellulose with a solvent soluble in a givensolvent, incorporating in the colloid a solid body soluble in the givensolvent, and

then treating the colloid with the given solvent, and at a temperaturebelow the boiling point of the resulting solution, thereby tosimultaneously remove the nitrocellulose solvent and the solid ;bodywhile retaining such solvent in said solution.

5. The method of preparing nitrocellulose propellent powder whichconsists in colloiding with a solvent soluble in a given solvent,nitrocellulose less than 50% of which is soluble in the first namedsolvent, incorporating in the colloid a solid body soluble in the givensolvent, and then treating the colloid with the given solvent, and at atemperature below the boiling point of the resulting solu tion, therebyto simultaneously remove the nitrocellulose solvent and the solid bodywhile retaining such solvent in said solution.

6. The method of preparing nitrocellulose propellent powder whichconsists in colloiding nitrocellulose with a solvent mixture of ethylether and ethyl alcohol, incorporating a water soluble solid body in thecolloid, and then treating the colloid with water, and at a temperaturebelow the boiling point of the resulting solution, thereby to simultaneously remove the solvent and solid body while retaining the solventin the solution.

7 The method of preparing nitrocellulose propellent powder whichconsists in colloidmg with a solvent mixture of ethyl ether and ethylalcohol, nitrocellulose less than 50% of which is soluble in saidmixture, incorporatin a water soluble solid body in the colloi and thentreating the colloid with water, and at a temperature below the boilingpoint of the resulting solution, thereby to simultaneously remove thesolvent and solid body while retaining the solvent in the solution. i

8. The method of preparingnitrocellulose propellent powder whichconsists in colloidmg nitrocellulose with a solvent mixture of ethylether and ethyl alcohol, incorporating a water-soluble solid body in thecolloid, forming the resulting composition into desired shapes, and thentreating'the shapes with water above the boiling point of ethyl etherand below 65 C. and in such quantity as to give a solution of a boilingpoint above 65 C. to thereby .simultaneously and in a single stepsubstantially remove solvent and solid body from the powder.

9. The method of preparing nitrocellulose propellent powder whichconsists in colloid-' mg with a solvent mixture of ethyl ether and ethylalcohol, nitrocellulose less than 50% of which is soluble in saidmixture, incorporating a water-soluble solid body in the colloid,forming the resulting composition into. desired shapes, and thentreating the shapes with Water above the boiling point of ethyl etherand below C. and in such quantity as to give a solution of a boilingpoint above 65 C. to thereby simultaneously and in a single stesubstantially remove solvent and solid bo y from the powder.

In testimony whereof I aflix my signature.

WALTER PHILIP REGESTEIN.

